This invention relates generally to refrigeration systems and, more particularly, to a device for controlling the flow of refrigerant from the condenser to the evaporator of a chiller system.
In centrifugal chiller refrigeration systems, it is necessary to regulate the flow of liquid refrigerant from the condenser to the evaporator, or cooler, of the system. In doing so, it is also necessary to prevent the flow of refrigerant gas from the condenser to the cooler. Heretofore, this has been accomplished in any of various ways. One approach is that shown in U.S. Pat. No. 5,009,079 issued on Apr. 23, 1991 and assigned to the Assignee of the present invention. This approach was simple and was responsive to the level of liquid refrigerant in the sump while, at the same time, preventing any bypass of refrigerant gas to the cooler, a feature which is particularly important when using high pressure refrigerant such as R-22.
A problem that the Applicant encountered with the above described patented apparatus was that the cylindrical sleeve that was slideably mounted on the outer side of the cylindrical standpipe member tended to hang up on the standpipe or cycle up and down continuously. This was found to occur because of undesirable axial and/or radial forces that tended to act on the sleeve. This was caused, in part, by the differential pressure between the condenser and the cooler. That is, the pressure within the condenser, and that on the outer side of the sleeve and standpipe, is typically about 210 psi, while the pressure in the evaporator, and also on the inner side of the standpipe, is about 80 psi. Thus, if the sleeve tends to move to a non-symmetrical position with respect to the standpipe, then this pressure differential was found to bias it to that position and to thereby cause a hanging up of the sleeve on the standpipe. As a result, the device is not responsive to the level of refrigerant in the sump, and inefficiencies occur.
It is therefore an object of the present invention to provide an improved refrigerant flow metering apparatus for a centrifugal chiller system.
Another object of the present invention is the provision for a refrigerant flow control device that is responsive to the level of liquid refrigerant in the condenser.
Yet another object of the present invention is the provision for a refrigerant flow control device which is not adversely effected by the pressure differential across the device.
Still another object of the present invention is the provision in a centrifugal chiller system, for a refrigerant flow control device which is simple and reliable in operation.
These objects and other features and advantages become more readily apparent upon reference to the following description when taken into conjunction with the appended drawings.